1. Technical Field
The present invention relates to an improvement of a motor employed in the rotational drive device of the computers and peripheral equipments.
2. Description of the Prior Art
A rotor as rotating member of the motor is adapted to be journalled by means of bearing means as shown in FIG. 3. The bearing means comprises a pair of ball bearings 21, 22 fitted on a shaft 23. The bearings 21, 22 are spaced apart for example by means of spacer 24 secured on the shaft 23.
Reduction of the equipments size is the major problem of the computers and peripheral equipments such as the hard disk drive device. That is, it is desirable to make the rotor of the motor utilized in these equipments and the bearing means for supporting the rotor as small as possible.
The way which can be adopted to reduce the size of the bearing means is to miniaturize both ball bearings of the pair. However, this countermeasure leads to the reduction of the diameter of the shaft.
The shaft of reduced diameter provides a problem of reduced mechanical rigidity to impair the reliability and vibration-proof property of the motor. Further, in case the shaft of reduced diameter is used in the precision equipment such as hard disk drive device, the shaft becomes resonant with members of the equipment surrounding therearound e.g. the casing of the device. That is, the reduction of the resonance property will be accompanied by the reduction of the reliability of the equipment.
The object of the present invention is to provide a vibration-proof small size motor of high endurance including a compact enough double row bearing apparatus having a shaft of sufficient mechanical rigidity.